I have an ARM docker container that never launches within CircleCI

I have an ARM docker container that I have constructed, based on the show0k/miniconda-armv7 container that @show0k created. I wrote in detail about this here on Stack Overflow.

The gist of it is that my container, though it works perfectly on my desktop machine (without binfmt_misc support), never actually starts in Circle, or I get an error message Unexpected preparation error: Error response from daemon: Container *** is not running.

I would really appreciate help in diagnosing this since I can think of no way forward now.